House Space and Aeronautics subcommittee chairman Mark Udall warns that the report is a wake-up call.

"We need to understand what happened and why, whether anyone is going to be held accountable, and what the agency is going to do to fix these apparently deep-seated problems," he says.

The report released by NASA found "heavy use of alcohol" inside the standard 12-hour "bottle to throttle" abstinence period for flight crew.

NASA has recently regained its confidence after the 2003 break-up of Columbia with seven aboard, and years of testing to prove the reliability of its shuttle program, as well as its management procedures.

Kidnap

But in February NASA's reputation was sullied again when astronaut Lisa Nowak allegedly tried to kidnap a woman dating another astronaut.

In the wake of Nowak's arrest, NASA set up an internal panel to review astronaut health, and was handed reports of astronaut drinking.

"That's not the 'right stuff' as far as I'm concerned," says Bart Gordon, chair of the House of Representatives science and technology committee, alluding to the book and 1983 film about early NASA crews, The Right Stuff.

Air Force physician Colonel Richard Bachmann, who authored the report, told reporters one drinking incident came ahead of a shuttle mission that was eventually delayed.

The astronauts then wanted to fly on a T-38 supersonic jet used by NASA, he says, without giving more detail.

Drunk

The second case involved a Russian Soyuz mission bound for the International Space Station, Bachmann says.

Bachmann says there is "no way to know if they were isolated incidents or the top of large iceberg".

NASA says: "Both flight surgeons and astronauts identified some episodes of heavy use of alcohol by astronauts in the immediate pre-flight period which has led to flight safety concerns."

"However the individuals were still permitted to fly," it says.

The panel interviewed 14 astronauts, eight flight surgeons, five family members and other staff for the 12-page report, which notes that astronauts lack regular mental-health assessments and feel pressure to hide their problems.

Sabotage

There was more bad news for the space agency last week when NASA officials say workers found a computer due to be transported by shuttle Endeavour in an August mission to the International Space Station had been apparently sabotaged, its wires cut.

"One of our subcontractors noticed that a network box for the shuttle had appeared to be tampered with," a NASA spokesperson says. "It is intentional damage to hardware."

Workers who discovered the computer damage at the subcontractor's facility, not at NASA's, had notified the space agency "several days ago", the spokesperson says. "There is an ongoing investigation."